Why Did The US Never Adopt The Metric System? It's About Pirates

Maybe the pirates needed a new measurement that wasn't just "booty".


Jack Dunhill


Jack Dunhill

Social Media Coordinator and Staff Writer

Jack is a Social Media Coordinator and Staff Writer for IFLScience, with a degree in Medical Genetics specializing in Immunology.

Social Media Coordinator and Staff Writer

pirate flag skull and crossbones

The US tried to adopt the metric system, but pirates made sure it never happened. Image credit: donfiore/

A meme as old as time, people from around the world love to lay into Americans for not joining the metric system like pretty much every single other nation in the world. Special examples include using giraffes to measure asteroids, stretched-out cats for furniture, and classic American bald eagles for social distancing – the US will literally use anything but the metric system. 

But how did we get here? Why did the US not adopt the same system as everyone else? Well, as usual, it comes down to dastardly pirates. 


Why doesn't the US use metric? It's pirates

Coming off the back of their victory over the British and forming one nation of many states, the new United States of America had to address the fact that everyone was using different measurement systems. It becomes very difficult to do trade when no one quite understands what each thing weighs, so the government began a search for a unified system. Europe was trailblazing various methods, but the French had a particularly interesting option that seemed to make perfect sense: what we now know as the metric system. 

Perhaps the most important part of unifying the world to one unit was creating the perfect kilogram weight. This was a complicated affair, and in the late 1700s small cylinders (called “graves” but later named kilograms) were made that represented the mass of one cubic decimeter of water at 4°C (39.2°F) as closely as science allowed. If the US was to join in the fun, they would need to get their hands on a grave. 

One of the original grave prototypes from 1793. Image credit: NIST Museum via Wikimedia Commons (public domain)

Thomas Jefferson, Secretary of State at the time, wrote a letter to France enquiring about adopting the new system, and France answered by sending Joseph Dombey, a French scientist, and a one-kilogram copper weight on a voyage to the States. Sadly, for Dombey and the crew, they were never to make it across the Atlantic. 

A harsh storm hit the vessel, blowing them far off course. When the storm cleared, Dombey and the crew found themselves in the Carribean Sea, which – if you’re a 18th-century sailor – is possibly the last place you want to be. The vessel was captured by privateers, a type of pirate who were helped by the British government to attack shipping lanes, and the entire crew were imprisoned in Montserrat. Awaiting a ransom that never came, Dombey and the crew died in captivity. 


Ironically, the pirates weren’t interested in how heavy a kilogram was and didn’t care for the grave, if they even knew what it was. The contents of the ship were auctioned off and the kilogram that could’ve redefined American measurement was purchased by Andrew Ellicott, who passed it down through his family until 1952, when it was given to what is now known as the National Institute of Standards and Technology, according to NPR

The US went on to develop their own units, called customary units, which were used until the US and UK made efforts to align their unit definitions in 1959, creating the measurements that are most often used today in conjunction with other systems. 

While it’s nice to think that pirates may be the sole reason why the US never went metric, there are plenty of other reasons. Efforts have been made across the centuries to join the rest of the world, but costs, time, and public opinion have prevented the switch from ever happening. However, the original reason, the reason that metric never even touched down on the shores of the US, is absolutely pirates


  • tag
  • weight,

  • measurements,

  • pirates,

  • kilogram,

  • metric system